Early Universy Molecular Hydrogen Formation
The chemistry of the Early Universe is much less complex than the reaction networks in today's interstellar molecular clouds. As only three elements (H, He, Li) have significant abundances, some twenty chemical reactions have to be considered. The formation of the First Stars relies heavily on radiative cooling through H2 rovibrational transitions since the levels in atomic hydrogen are two far-spaced for efficient cooling at temperatures <10000 K. Without H2 cooling the collapse of a primordial gas cloud would be counteracted by the intrinsic pressure and the star formation would stall. Until recently the formation of H2 under primordial conditions was not well understood. The dominant formation mechanism is the process H- + H → H2 + e-. Measurements for the rate coefficient of this reaction existed only at room temperature and theoretical calcuations disagreed with the measurements and among each other.
At Columbia University we have built a dedicated Merged Beams Apparatus to study this reaction for a wide range of collision energies.
Figure: Columbia Merged Beams Setup at the Nevis Laboratory.
Our results were published in Science Magazine in July 2010 [Kreckel et al. Science 329, 69 (2010)]. A free link is provided through the Columbia Webpage. Below are some links to websites that covered our research. A full list can be found on the web page of D.W.Savin.
1) Conditions for universe's first stars ..., Space on MSNBC.com, July 1, 2010.
2) A Star is Born ... But How?, NSF press release .
3) Researchers shed light on birth of first stars, Astronomy, July 8, 2010.
4) Die Entstehung der ersten Sterne, astronews.com (Germany), July 2, 2010
5) How Stars Were Born, South Asian News (India), July 7, 2010.
6) Die Entstehung der ersten Sterne, Wissenschaft Aktuell (Germany), July 2, 2010.
7) Researchers Shed Light on Birth of the First Stars, Space and Earth Science, July 7, 2010.
8) How Stars Were Born IndiaVision (India), July 7, 2010.
9) A Star is Born...But How?, Popular Mechanics (South Africa), July 6, 2010
10) Die Entstehung der ersten Sterne, pro-physik.de (Germany), July 2, 2010